In subsea oil and gas exploration, the drilling system or wellhead may be located many thousands of feet below the sea surface. Specialized equipment is therefore used to drill, produce and process oil and gas on the sea floor, such as subsea trees, processing systems, separators, high integrity pipeline protection systems, drills, manifolds, tie-in systems and production and distribution systems. Such equipment is commonly controlled by a number of types of valves, including blow-out preventers to stop the unintended discharge of hydrocarbons into the sea.
With existing systems, such valves are typically operated hydraulically by providing pressurized hydraulic fluid from a surface vessel down to the wellhead. Large hydraulic power lines from vessels or rigs on the ocean surface feed the ocean floor drilling, production and processing equipment, and the many subsystems having valves and actuators. However, such lines are expensive to install and maintain and in some cases may not be feasible, such as at depths over 10,000 feet or under the arctic circle ice caps.
Accordingly, it would be desirable to provide an actuator that would not require such an umbilical connection from the surface and that would still operate with the desired force and functionality.